Van de Loo, et al., 1995. An oleate
12-hydroxylase from Ricinus communis
is a fatty acyl desaturase homolog. P.N.A.S.
is a classic for its pioneering approach, 'high-throughput DNA sequencing' to
try to identify a gene for a specific enzymatic function, where no
directly homologous sequences are available. While most of the technical
aspects are beyond our course, the key technique is one of differential
hybridization, which allows the identification of cDNA
clones in a library by comparing their abundance in 2 tissues, ie seed vs leaf.
two guide your reading. We'll discuss on
Thurs, Oct 5th so please submit your responses at that time.
that prior to this, no known sequence data for this enzyme and its gene were
known, what are the criteria the authors are using in their search?
2. What is
the most direct proof the authors have that they have identified the correct
gene? (Are you convinced?)
promoter is being used to drive expression of the cloned gene in transgenic
tobacco. Would you expect expression in leaf tissue as well as in seeds?
4. Is the
putative new hydroxylase gene expressed in leaves of the transgenic tobacco
plants? Do the authors show any data on this?
Speculate on why there is such low levels of ricinoleic
acid in the transgenic plants.